This invention relates to a means for attaching implements such as buckets and hammers to a backhoe or similar earth-working machinery. Typically, with such machinery, a dipperstick and a linkage arm connect and control the implement. The implement may be attached directly to the dipperstick and linkage arm or it may be attached by means of a hitch.
Attachment directly to the dipperstick and linkage arm is accomplished with a pair of removable pins. Each pin is manually inserted through a pair of opposing apertures in mounting flanges on the implement and through openings at the end of the dipperstick and at the end of the linkage arm.
Attachment by means of a hitch requires only one pin to be removably inserted. The hitch is an interface between the implement and the dipperstick arm, its top side being affixed at two points to the dipperstick and linkage arm. The bottom of the hitch has a hooked jaw at one end and a hollow sleeve at a second end. On the implement, a first pin is affixed between a first pair of opposing apertures. During attachment, the hooked jaw is remotely moved to engage this first pin. The hitch is then manipulated so that the second pair of opposing apertures on the implement is aligned with the hollow sleeve at the second end of the hitch. The second pin is inserted through these apertures and through the hollow sleeve. Thus, there are four points of attachment.
A particular type of hitch is embodied by a coupler manufactured by the J. I. Case Company. The coupler is similar to the typical hitch described above, except that the second end of the hitch attaches at the same place as the dipperstick and the implement. It can be thought of as a "three point" hitch. To achieve the third point of attachment, the second pair of opposing apertures in the implement must be aligned with both the hitch and the dipperstick before the second pin can be inserted through them.
Construction machinery such as backhoes is heavy and rugged, and any implements for this type of equipment must also be heavy and rugged. Being of large size and of heavy material, such equipment is difficult to manipulate, assemble and adjust. The uses to which this type of equipment is put contributes to difficulty in attaching, adjusting, and manipulating implements.
As explained above, both the direct method and the hitch method of attachment require two pairs of opposing apertures in mounting flanges on the implement. Depending on the method used, pins through these apertures must be inserted through whatever is being connected. Specifically, hollow sleeves, bosses, or jaws on the dipperstick, the linkage arm, or the hitch must be in alignment.
It is easy to see how the implement, the dipperstick, the linkage arm, or the hitch may become bent or be otherwise distorted through manufacturing error, damage, misuse, or uneven wear. This will destroy the alignment of the attachment means. Thus, improper alignment of parts through which a pin must pass is one parameter that inhibits attachment and removal of various implements.
When a hitch is used, there is another parameter that is critical to implement attachment and removal. This parameter is the relationship of two distances: (1) the distance between the jaw and hollow sleeve of the coupler, and (2) the distance between the two pairs of opposing apertures in the implement. Because hitches and implements are not always standard in size, these distances may not match. The result is that the hitch and the implement cannot be aligned to permit insertion of the second pin.
As a result of these two types of misalignment, pins must often be strenuously hammered in and out, resulting in damage to the pins themselves or to the implements, the dipperstick, or the linkage arm, or the hitch if one is used. Another result of misalignment is the use of shims, which are not secure and may contribute further to uneven wear. To avoid these problems, this invention uses a pair of eccentrically-bored fittings, which are permanently mounted inside opposing apertures on the implement.
Eccentricity is defined as the distance of the geometric center of a revolving body from the axis of rotation. In general, eccentrically-bored sleeves can be used to compensate for misalignment when a shaft of one piece of equipment must be received into a hole in another piece of equipment. Rotating an eccentric sleeve is desirable when it is difficult to move the equipment itself. This general application of rotatable eccentric sleeves is demonstrated by U.S. Pat. No. 3,385,624. This patent discloses an adjusting device used to align a bolt of a door into a socket of a door frame.
Eccentricity is used with cams to adjust rotation to translation movement. In an eccentric cam, the shaft is displaced from the geometric center. In U.S. Pat. No. 4,626,047, an eccentric sleeve in a cam is used to adjust the cam so that two pieces of equipment may be latched together. U.S. Pat. No. 3,120,281 discloses an eccentric cam used to adjust a ripper tooth attached to a front loader. Eccentrically-bored sleeves have been used in shaft bearings to adjust the throw of the shaft. In U.S. Pat. No. 1,565,264, such sleeves are mounted in a shaft bearing and are manually rotated relative to each other.
Eccentricity has been used in bushings to adjust distances and angles between two machine parts. In U.S. Pat. No. 2,159,348, a square bushing with an eccentric bore may be removed and reinserted in different positions to vary the angle of an earth moving blade. In U.S. Pat. No. 2,859,058, a bushing having an eccentrically-positioned bore is used in a connection between two machine parts. The bushing is manually rotated to adjust the distance between the centers of two parts.
Eccentrically-bored sleeves have also been used in shaft bearings. In U.S. Pat. No. 1,571,557, two eccentric sleeves are mounted in a journal bearing. The sleeves may be manually rotated relative to each other to align the shaft.
Eccentric bores in a backhoe hitch are described in two pending patent applications. International Publication No. WO 85/0440 and U.S. Ser. No. 895,808 disclose an assembly in a hitch. A pin is inserted through a single elongated bore, which is eccentric to the bushing. In WO 85/0440, the bushing is rotated with a tool inserted into apertures in the bushing. In U.S. Pat. Ser. No. 895,808, the bushing is freely rotatable and adjusts by means of a specially-designed pin.